Hi everyone, I recently purchased a 2017 CAT 304E2, serial ME402200. It was advertised as having no hydraulic function but the engine ran fine. Machine has ~2,500 hours. Based on that info I believed the problem to be either the safety switch in the cab or a stripped hydraulic pump coupler. When I was loading the machine I was told that it had actually been dropped off functioning normally and had been driven off the trailer and into place to be sold...and at some point in the time between getting dropped off and getting inspected/listed the hydraulics decided not to work any longer. The machine starts up fine and certain functions will rev the machine up from idle with the auto idle feature. I believe they are the blade, boom pivot, and hydraulic coupler. These functions also barely work. The blade will raise about 1cm from the trailer deck and can go back down. The quick coupler appears to work (at least the jaw I can see from inside the machine), and the boom will pivot left and right a small amount. I can't tell if it will go further because the coupler is resting on the trailer and I think that might be preventing it from going further, but it's enough that the cab moves a small amount. All of these working functions work veryyyy slowly. No functions that are controlled by the joysticks appear to be working, even slightly. There are two fault codes logged in the machine from about 30 hours ago, 2212-5(1) Aux #1 Port A Solenoid Current Low, 2211-5(1) Aux #1 Port B Solenoid Current Low. I don't really believe these are causing the issue as that appears to be just for the thumb and is from ~30 hours prior to the current machine time. Based on the machine idling up with the auto idle when some functions are engaged I am led to believe that the safety switch is functioning. Based on the very small amount of hydraulic function I am led to believe that the coupler is in tact. I am going to try to get a borescope into the housing and look to see if this is the case though just to be safe. Can anyone point me in the right direction to start looking? I'm guessing there's an electrical issue of some sort but electrical issues are not my forte. Thank you
I found that the bucket functions are also working very slightly. I just tried swapping the travel speed and hydraulic lockout solenoids and that didn't improve anything. Trying to work through the electrical diagram now to see what else it could be... I also found that when I idle the machine up and try to use functions that aren't working the machine turns the idle down even though I believe I've got auto idle turned off.
Following to learn, but this is above my understanding level.
No solution yet. The hydraulic lockout solenoid is getting signal and activating the electromagnet. Pulled the solenoid out and it's not entirely clear if it's moving much or not. I swapped it and the speed solenoid a few times and never got either to activate the hydraulics (if that's the issue). I may order a solenoid and see if a new one fixes it, but I feel it's unlikely that both the speed and lockout solenoid are dead. I guess my next step is ordering a hydraulic pressure testing kit to confirm the pump is spinning and making pressure. I may have to cave and buy the entire service manual for this one, I'm not sure.
Judging on what you said in first post I think I would be looking for critter damage to a wiring harness somewhere first
I could certainly believe that might be the problem here. Where would you start to look? I really am not an electrical person unfortunately. I was able to verify that the dead mans switch/safety switch seems to be working. The machine won't start with the armrest down and it does rev up when using some functions (the two toggle switches on the joysticks) I believe. We also verified that the solenoids were getting a good signal. For the hydraulic lockout solenoid we could measure 12v on it when the armrest was down but not when it was up. For the speed toggle solenoid it would change based on if it was in rabbit or hare mode. I guess my question is...what electrical connection could be severed and causing these issues?
look around pump and ecm
I looked around a bit and didn't see anything today, but will take another look on Friday. It didn't seem like there's many wires going to the pump in general though.
Toomuch issues. Have you checked oil condition? Checked pressure at pump outlet?
Oil looks good - it's on the lower side of the sightglass but still above the lowest line. I'm going to pick some up and add it but haven't had a chance to stop at a store with the holidays. I do not have a pressure testing kit. I'm looking around to see if there's one available to rent locally but haven't had any luck as of yet.
I was luckily able to get a pressure tester made by a hydraulic shop today. According to my pressure gauge, it looks like both the main and pilot pump have no pressure (at least not measurable), except on initial start up they both appear to have a ~50PSI jump for a second, but once the machine runs...nothing. I pulled the pump off and I believe the coupler looks okay, but I can't be 100% certain. I could not find any pressure relief valves to see if they're stuck open. I'm not sure what they look like or where they're located within the system. There are no electrical connections to the pump system, so no wires that could be bad as far as I know. Any ideas, or is it just my pump needs to be replaced/rebuilt?
I ordered a new coupler and was able to work on replacing it this evening. I pulled the counter weight off the machine and exposed the pump fully and slid it out to confirm the coupler was indeed bad before pulling the housing fully. Unfortunately, the coupler seems fine. I then space it out a bit and turned the machine on with a small gap between the pump and bell housing and confirmed that it spins. Still no pressure at main pump or pilot pump taps so tried the only thing I could think of and adjusted the pressure relief valve and the other adjustment to the left of it on the pump (I forget the name) to see if I could get any pressure. I was able to get the main pump up to about 2,000 PSI, but that was with the PRV fully screwed in and some adjustment on the other valve. The pilot controls were reading ~800, so I backed it down so the pilot was in normal range. Still no functions on the control, which says to me there's not really any flow. If there was pressure in the first place but no function I would guess an obstruction in the system somewhere, but since there was no pressure without significant/maxed out pressure, and it's still about half what it should be...I am leaning towards the pump itself being the problem. Anyone else have other ideas/thoughts? Anything I might be missing before I order a new pump? Thanks
Dang. I feel for you. It is hard to keep trying things and to keep coming up blank. Could it be on the suction side? Something as dumb as a kinked hose, plugged filter, low hydraulic fluid, dead rodent in the tank? Just throwing ideas out there.
Can't say it's been super fun, haha I sort of looked into this the other day, but not with the machine running. I cracked the valve open at the low point of the system and drained some fluid out to make sure there was flow getting to the pump itself. I guess I figured if there was a flow problem to the pump it would be making some sort of noise, and it's completely silent. The sightglass is reading above the minimum line. I don't have a flow testing setup, so I can't check to see what sort of flow I have unfortunately. Appreciate the ideas, keep them coming...
The problem has been SOLVED! I have been messaging with Nige throughout this saga and he has been giving me some great ideas of things to check. Earlier this week I removed the hydraulic return filter and cut it open to look for debris which might indicate the pump had failed and sent metal into the system. I did find some small pieces, and more in the filter housing, but seemingly not an alarming amount. This gave me some pause as my next step was to order a new pump but Nige suggested looking at the scavenge filter in the tank itself next to see if it could have been blocking flow to the pump partially. I also had been in touch with a local equipment mechanic who seemed skeptical that it would be the pump, so he was trying to steer me towards checking other options, but he wasn't available to come out to look at the machine until later this week. So I came up with a plan. I put an order in for a new hydraulic filter as I had cut the existing one up, I also picked up 20 gallons of hydraulic oil (it was unclear if the system on this machine was ~9 gallons or ~16 gallons) and while I was at it I tossed a new hydraulic lockout solenoid in my order as well. When I was originally testing the solenoids and armrest switch I had tested the solenoid wiring and confirmed both were getting 12v when they should, I also confirmed that the electromagnets were magnetizing and holding a screw driver...but I couldn't get one of them to open/close in any way that I could visually tell, and the other just cracked open a hair. The solenoids also didn't click or make any noise, but I wasn't super familiar with them so didn't know if these ones would or not. I figured the odds of both solenoids being junked were slim, but possible, so I ordered a new solenoid just to give it a try. While I waited for my parts order to arrive I began reading through the main pump operations in the service manual and it seems like if there's no pressure required the pump can go into a standby mode where it derates itself. I was skeptical that this could be what was happening because I figured if the pump went into the derated mode it would put out less pressure, not no pressure at all...so I wasn't sure that this was what was happening but thought hey, maybe it IS the lockout solenoid and if it isn't opening then the hydraulic fluid is bypassing the main valve block, coming back around, and then the pump is sensing there's no resistance and derating itself. Seemed like a long shot but what the heck. My plan for the day was to install the new filter, add some hydraulic fluid back to the system, test the new solenoid outside the machine to see if it clicked or opened more than the other ones, then if it didn't seem any different I was going to drain the entire system and pull the scavenge filter to check for clogs. If it wasn't clogged I was most likely going to order a new pump. So I swapped the filter, added the fluid, and plugged the new solenoid into the wiring harness but kept it outside the machine. Got in the cab, turned the key to the on position and put the armrest down and...thunk! The solenoid made an audible noise. So I got a bit excited and thought hey, maybe this is the issue! I installed the solenoid, went back to the pump and backed the pressure relief valve and load sensing valve way back down, and started the machine up. Hydraulics are back! Sorry for the long winded post but I figured maybe sometime in the future somebody might stumble across a similar issue and want to see how I worked through it. I was shocked it was the solenoid as I figured I ruled that out when I swapped them round, but I guess I just had two bad eggs. I'll get another one on order this week as it seems my machine is stuck in rabbit mode now haha Thanks to everyone who gave input and ideas, especially Nige. I appreciate the help and am glad to have the machine functioning!
That is great news! I'm glad your perseverance paid off!
I'm gald you got it running. who would have thought of two bad solenoid valves happening at the same time.? I do have a theory (see next paragraph) that maybe some of the particles circulating in the system have got into the spools of both those valves and seized them up. So despite the fact that the coils are magnetising correctly the spool in the valve won't move. I have messaged you separately but the quantity of bronze shrapnel you found in the filter element and in the bottom of the filter housing is NOT normal. Something is coming apart somewhere - you just have to find out what it is.
Thanks, yes, great news and happy to have it working again. Now to sort out why it happened in the first place. Yeah, it does certainly seem odd that both would fail simultaneously and having some shrapnel in the system could be an explanation. I won't really be using the machine until spring, but I'll make sure to check the filter out and the housing after using it for a little bit and see if the debris has returned or if it just never got cleaned out. Another hint would be if a solenoid fails again I suppose. I may also try to see if I can look at the solenoid I pulled out and see if there's anything obvious blocking it up. Not sure how easy they are to take apart, but I'll sort it out.
Just curious you have any pictures of the brass -bronze debris ??
Here's 3 images: The first is the filter I cut up and inspected. I cut two sections and this one had more debris than the other. The second image is the bottom of the filter housing which had some metal in it, and the third is an image of the shop towel I wiped the filter housing out with. The machine has ~2,500 hours on it and the computer shows that someone entered that they swapped the filter and fluid ~600 hours ago which would be a bit early, but around the time it was due to be swapped.
I hate to say the only places I know there is brass are the slippers on pistons in pumps and motors and the port plates but i would think a port plate sheading that much you would have a weak function
Yeah, we'll see what happens when I get to running the machine in the spring. If more debris accumulates, which seems likely I suppose, then it'll be time to investigate swapping the pump. The machine functions and I was able to get it unloaded at my house for the winter, so it's not stuck on a trailer any longer and that's all that really matters at this point!
going to sound dumb.. but I took apart one of my hydraulics on my old backhoe a few years ago. anyway, I plugged the holes on the lines with one of those blue shop towels. Jammed it in there pretty good with a screwdriver. So, a week or so goes by, and I pull out the blue shop towels and reconnect. Everything works great for about a minute and then super slow almost nothing on my hoe. loader bucket worked fine. turns out after a bit of swearing that I had not fully removed all that blue shop towel and it got jammed in the valve block in such a way that I had no fun getting it out of there, but after pulling a bunch of valves apart - I got out all the bits and chunks of towel - which really all collected in one area, but were enough to nearly impeded flow. One of those stories you feel dumb telling people about, but we all learn from something. anyway... that probably won't help you unless you know someone did something dumb like that to your machine...
It may sound dumb but you aren't alone seen that more than once Easy to do if the guy before you put two in instead of one and you only remove one!! Also saw them leave a rag in intake piping on a new certified rebuild 992 it sure made it smoke fortunately it didn't hurt the turbo